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| United States Patent |
5,077,112
|
|
Hensel
, et al.
|
December 31, 1991
|
Floor covering with inorganic wear layer
Abstract
A floor covering is a laminate including a hard inorganic wear layer
deposited on a support, preferably by a reduced pressure environment
technique such as ion assisted physical vapor deposition. The support may
be selected from metal foils, films or sheets and plastics, rubbers or
mineral/binder systems. The preferred support materials include stainless
steel and polyester sheet molding compound.
| Inventors:
|
Hensel; Robert D. (Millersville, PA);
Ray, Jr.; Leonard N. (Lancaster, PA);
Reuwer, Jr.; Joseph F. (Lancaster, PA);
Wisnosky; Jerome D. (Lancaster, PA)
|
| Assignee:
|
Armstrong World Industries, Inc. (Lancaster, PA)
|
| Appl. No.:
|
507875 |
| Filed:
|
April 12, 1990 |
| Current U.S. Class: |
428/76; 427/488; 427/527; 427/529; 427/531; 427/585; 428/195.1; 428/457; 428/688; 428/698; 428/908.8 |
| Intern'l Class: |
B32B 003/00 |
| Field of Search: |
428/195,457,688,698,908.8
427/54.1,96
|
References Cited
U.S. Patent Documents
| 4604181 | Aug., 1986 | Mirtich et al. | 204/298.
|
| 4614556 | Sep., 1986 | Fry et al. | 156/78.
|
| 4702963 | Oct., 1987 | Phillips et al. | 428/426.
|
| 4743510 | May., 1988 | Nemeth | 428/455.
|
Other References
Eli Yablonovitch et al., Appl. Phys. Letter, 51(26), Dec. 28, 1987, pp.
2222-2224, Article Entitled "Extreme Selectivity in the Lift-Off of
Epitaxial GaAs Films".
L. A. Clevenger et al., Appl. Phys. Letter, 52(10), Mar. 7, 1988, pp.
795-797, Article Entitled "Reaction Kinetics of Nickel/Silicon Multilayer
Films".
Ryszard Lamber, Journal of Materials Science Letters 5 (1986), pp. 177-178,
Article Entitled "Thin Boehmite Films: Preparation and Structure".
J. C. Huling et al., J. Am. Ceram. Soc., 71[4] C-222-C-224 (1988), Article
Entitled "A Method for Preparation of Unsupported Sol-Gel Thin Films".
Trade Literature Entitled, "Interior/Wall Facings From AllianceWall",
AllianceWall, Norcross, GA 30092.
Trade Literature Entitled, "Armor-Stat Dissipative Floor Tile", 1988,
Trio-Tech International Static Systems, San Fernando, CA 91340.
|
Primary Examiner: Ryan; Patrick J.
Claims
We claim:
1. A floor covering comprising a support and a wear layer deposited on said
support by a reduced pressure environment technique selected from the
group consisting of sputtering, plasma polymerization, physical vapor
deposition, chemical vapor deposition, ion plating and ion implantation,
wherein the wear layer comprises a hard inorganic material.
2. A floor covering comprising a support and a wear layer deposited on said
support by a reduced pressure environment technique, wherein the support
comprises a metal component selected from the group consisting of a foil,
a film and a sheet.
3. The floor covering of claim 2, wherein the metal component has a
thickness of between 0.007 inches and 0.5 mils.
4. The floor covering of claim 2, wherein the metal component is a steel.
5. The floor covering of claim 2, wherein the support further comprises a
decorative layer overlying the metal component.
6. The floor covering of claim 1, wherein the support further comprises a
conformable layer capable of inelastic deflection.
7. The floor covering of claim 1, wherein the support comprises plastic,
rubber or a mineral/binder system.
8. The floor covering of claim 7, further comprising an ink which diffuses
into the support.
9. The floor covering of claim 7, wherein the plastic is a thermoset
plastic.
10. The floor covering of claim 1, wherein the wear layer is discontinuous.
11. The floor covering of claim 1, wherein the wear layer is at least 1
micron in thickness.
12. A floor covering comprising a support and a wear layer deposited on
said support by a reduced pressure environment technique, wherein the wear
layer comprises a hard inorganic material selected from the group
consisting of metal oxides and metal nitrides.
13. The floor covering of claim 12, wherein the hard inorganic material is
selected from the group consisting of aluminum oxide, silicon oxide,
aluminum nitride, silicon nitride and titanium nitride.
14. The floor covering of claim 1, wherein the support is mounted to a base
layer, said base layer being capable of conforming to the irregularities
of a wood subfloor and capable of accommodating lateral movement of a wood
subfloor, the support being mounted whereby the periphery of said base
layer is exposed.
15. A floor covering comprising a metal support layer and a wear layer
consisting of hard inorganic material.
16. The floor covering of claim 15, wherein the support layer is capable of
inelastic deflection.
17. The floor covering of claim 15, wherein the floor covering is capable
of supporting a uniform 125 lbs/sq. ft. load with a deflection of not more
than one-five hardness of the span.
18. The floor covering of claim 15, wherein the hard inorganic material is
a fused ceramic.
19. A method of making a floor covering comprising
(a) providing a floor covering support, and
(b) depositing a wear layer of at least 1 micron in thickness on the
support by a reduced pressure environment technique selected from the
group consisting of sputtering, plasma polymerization, physical vapor
deposition, chemical vapor deposition, ion plating and ion implantation.
20. The method of claim 19, wherein the wear layer comprises a hard
inorganic material selected from the group consisting of metal oxides and
metal nitrides.
21. The method of claim 19, wherein the wear layer is deposited on the
support at a deposition temperature of no greater than 170.degree. C.
22. The method of claim 21, wherein the wear layer is deposited on the
support at a deposition temperature of no greater than 150.degree. C.
23. The method of claim 21, wherein the wear layer is deposited in a
thickness of at least 3 microns.
Description
BACKGROUND OF THE INVENTION
The invention relates to a floor covering. More particularly, the invention
relates to a floor covering having an inorganic wear layer which
preferably has been deposited on a support structure by a low pressure
environment deposition technique. Further, the invention is directed to a
multilayered floor covering in which each layer contributes to the wear
performance and installation characteristics and affects the performance
of the other layers.
Floor coverings having wear layers are well known in the art. Such wear
layers protect the decorative layer of the floor coverings and lengthen
the useful life of the floor covering. With the exception of ceramic tile
which are rigid and must typically be installed on a mortar bed and metal
floors such as steel plates, neither of which have a wear layer per se,
inorganic material is not used as the wear surface of floor coverings.
Inorganic materials are typically considered too brittle to be walked on;
particularly if a "thin" layer were to be placed over a flexible or
conformable support layer. Further, low pressure environment deposition
techniques have not been applied to the manufacture of floor coverings.
Reduced pressure environment techniques for depositing films of hard
inorganic materials include sputtering, plasma polymerization, physical
vapor deposition, chemical vapor deposition, ion plating and ion
implantation. Hard inorganic materials which can be prepared using these
techniques include metals, metal oxides, metal nitrides and mixtures
thereof; such as aluminum oxide, silicon oxide, tin and/or indium oxide,
titanium dioxide, zirconium dioxide, tantalum oxide, chromium oxide,
tungsten oxide, molybdenum oxide, aluminum nitride, boron nitride, silicon
nitride, titanium nitride, and zirconium nitride, as well as metal
halides, metal pnictides and metal chalogenides.
Often the partial pressures of key gases in the deposition environment are
controlled to effect chemical reactions between depositing metal species.
Therefore, a film formed on a substrate by reactive sputtering or reactive
deposition can be a compound derived from a metal and a controlling gas,
i.e., aluminum oxide produced by sputtering aluminum in oxygen. Sometimes
the controlling gases are used to sustain a plasma in the deposition
environment. Ion assisted deposition is a technique in which the
controlled gas is ionized and is used to bombard the deposition surface to
modify the morphology and physical properties of the resulting film.
A critical review of vapor deposition technology related to hard coatings
was presented by J. E. Sundgren and H. T. C. Hentzell in J. Vac. Sci.
Tech. A4(5), September/October 1987, 2259-2279. A more complete review of
techniques involved in formation of thin films in reduced pressure
environments is the book edited by J. L. Vossen and W. Kern, Thin Film
Processes, Academic, New York, 1978.
Recent articles on thin film preparation include Yabinouitch, E., Gmitter,
J. P., Haubison, J. P. and Bhat, R., Appl. Phys. Letter, 51(26), Dec. 28,
1987, 2222-2224 on etching Al/As to form free standing GaAlAs films;
Clevenger, L. A., Thompson, C. V. and Cammarata, R. C., Appl. Phys.
Letter, 52(10), Mar. 7, 1988, 795-797 on using commercial photoresists as
supports; Ryszard Lamber, Thin Boehmite Films: Preparation and Structure;
Journal of Materials Science Letters, 5(1986), 177-178; and Huling and
Messing, J. Am. Ceram. Soc., 71(4), 1988, C222-C224, on coating on camphor
and subliming to obtain free standing mullite.
Patents dealing with thin film deposition include: U.S. Pat. No. 4,604,181
and 4,702,963.
Reduced pressure environment techniques have been used to coat plastics
materials such as plastic bags to improve gas impermeability. However,
such coatings have been limited to about 0.5 microns in thickness.
While reduced pressure environment techniques have been used to form hard
coatings on surfaces such as automobile parts, there has been no
suggestion that such coatings could be successfully used as wear surfaces
for floor coverings. In fact, such coatings tend to be brittle when
applied in a substantial thickness. Thus, one skilled in the flooring art
would not expect reduced pressure environment deposited materials to
function adequately as a floor covering, particularly in the thickness
deemed necessary to protect the decorative layer of a floor covering.
Alliance Wall manufactures and sells wall coverings in which porcelain
enamel is fused to a steel sheet. However, use of a material as a wall
covering does not suggest that it would be acceptable as a floor covering.
Again, one skilled in the flooring art would not expect a thin sheet of
ceramic to withstand the long term abuse to which flooring is subjected,
particularly when laid over a resilient support structure and walked on by
a woman in high heels.
SUMMARY OF THE INVENTION
An object of the invention is to provide a floor covering that has the
appearance retention of ceramic tile (including stain resistance and gloss
retention), and resists cracking and brittle failure.
A further object is to provide a floor covering having an inorganic wear
layer which is flexible enough to be rolled around a reasonably sized
mandrel and therefore can be installed in a manner similar to present
resilient floor coverings.
Another object is to provide a floor covering laminate having the above
listed features and which is conformable to the subfloor on which it is
laid.
Such a floor covering has been made by depositing a wear layer of a hard
inorganic material on a support by a reduced pressure environment
technique. The preferred reduced pressure environment technique is ion
assisted physical vapor deposition; and the preferred support is
multilayered.
The preferred hard inorganic material is a metal oxide or metal nitride,
most preferably aluminum oxide, silicon oxide and silicon nitride.
Aluminum oxide, silicon oxide and silicon nitride form films which are
colorless, clear and of hardness similar to the dirt to which the floor
covering is normally subjected.
Preferred supports include a metal component such as a foil, a film or a
sheet. The metal support may be from 0.001" to 0.25" thick, preferably
0.003" to 0.1" thick. The preferred support is a stainless steel sheet of
at least 0.007 inches in thickness. Although a low carbon steel may be
used its performance is poorer. Preferably, the support includes a
decorative layer of fused glass or ceramic frit overlying the metal
component.
Since the glass or ceramic is a metal oxide which can be deposited by a
reduced pressure environment technique, the wear layer can be formed from
a glass or ceramic material. That is, the decorative layer can be the wear
layer.
Depositing a hard inorganic material on surface of a plastic, rubber or
mineral/binder system support substrate improves the wear resistance and
falls within the scope of the present invention. The plastic may be either
a thermoset or thermoplastic. The preferred thermoplastic is polyethylene
terephthalate. The preferred thermoset plastic is a crosslinked reinforced
polyester such as polyester sheet molding compound sold by Premix, Inc.
The thickness of the support should be between 0.0005" and 0.25".
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a first embodiment of the present
invention.
FIG. 2 is a perspective view of a second embodiment of the present
invention.
FIG. 3 is a perspective view of a third embodiment of the present
invention.
FIG. 4 is a cross-sectional view taken along line 4--4 in FIG. 3.
FIG. 5 is a cross-sectional view of a fourth embodiment of the present
invention.
FIG. 6 is a schematic representation of test setup to measure rupture
strain.
DETAILED DESCRIPTION OF THE INVENTION
Broadly, the invention is a floor covering having a hard inorganic material
wear layer and a support including metal or plastic. While the preferred
floor covering is a flexible laminate which has been deposited on a
support by a reduced pressure environment technique and which permits
installation similar to conventional resilient flooring, including
resilient tiles; the invention is intended to include rigid floor
coverings having a wear layer of reduced pressure environment deposited
hard inorganic material, and conformable floor coverings having a glass or
ceramic material applied to a metal support by means other than a reduced
pressure environment technique.
Metals and hard inorganic materials such as ceramics have unique
properties. Properly selected ceramics are hard enough to resist being
scratched by the grit particles in dirt. Properly selected metals should
be hard enough to support the ceramic and yet be flexible. Such a laminate
can be made in an atomistic deposition chamber by depositing on a thin,
properly tempered steel. This laminate could then be mounted on an
organic-polymer support layer to form a flooring structure. The support
layer conforms to the subfloor irregularities and accommodates lateral
movement of the subflooring structure. Although vacuum techniques could be
used in making such a flooring structure, current technology would enable
it to be made on a continuous, air-to-air production line.
No organic surface, either currently in existence or envisioned, possesses
sufficient resistance to loss of gloss and to other physical damage to
fully meet desired performance. Thick (1/4inch), hard ceramic tiles (Mohs
hardness of at least 7 and preferably 8.5) resist loss of gloss and other
physical damage extremely well.
The Mohs hardness of grit particles in dirt probably ranges between 6
(silicates) and 7 (silica). A rule of thumb among tribologists is that if
a surface is 1.5 Mohs units harder than a grit particle, the surface will
not be scratched by the grit particle. This applies when the grit particle
is between two surfaces of equal hardness. In a flooring situation, the
grit particle is usually between the relatively soft bottom surface of a
shoe and the floor surface. Therefore, the maximum downward force on the
grit particle is the resistance the bottom of the shoe offers to
penetration by the grit particle. The softer the bottom of the shoe, the
less downward force exerted on the particle. Consequently, the difference
in hardness between the grit particle and the flooring surface may not
need to be quite as large as 1.5 Mohs units. In any case, a Mohs hardness
of 8.5 is a reasonable goal for the ceramic film. However, wear layer of
Mohs hardness of about 5 or 7 have been shown to retain gloss level
despite larger scratches. Prior art organic wear layers have a Mohs
hardness of less than 3. Therefore a Mohs hardness of 3 or greater will
yield an improvement.
If formed by atomistic deposition, the ceramic-film wearlayer envisioned
for the laminate structure would be expected to be essentially stain proof
and to retain its gloss extremely well. The film would be expected to be
essentially stain proof because such films provide excellent corrosion
resistance for the substrates on which they are deposited. The film
retains its gloss and resists damage from grit particles because it can be
made sufficiently hard, approaching the hardness of the grit particles in
dirt, and may be supported on a support having proper stiffness.
Although ceramic film has both stain resistance and gloss retention, its
brittleness has prevented it from being used as a wear layer in a
resilient floor covering. Brittleness makes the ceramic film susceptible
to serious damage. However, by combining the ceramic film with a support
such as a sheet of metal or plastic with the proper characteristics, a
ceramic film may be used. If the support is sufficiently strong to give
the floor covering the ability to support a uniform 125 lbs/sq ft load
with a deflection of not more than one-five hundredths of the span, the
floor covering may be free standing. The ceramic tile does not have the
ability to perform when supported in a free standing manner. Laminate must
have the necessary physical properties as discussed below.
In order to understand why such a laminate should solve the problem of
brittle damage, it is useful to divide the types of forces causing damage
into two categories: (1) localized pressure and (2) impact.
Localized pressure occurs when a grit particle is pressed downward against
the ceramic surface. If the particle can force the ceramic film down into
the support layer on which it has been deposited, the ceramic film is put
into tension and fails. Ceramics, although strong in compression, are weak
in tension. To avoid such failure in tension, the support layer must
resist being indented when the grit particle is pressed against the
ceramic film. Actually, all the ceramic film does in protecting the
support layer from indentation is to spread the force over a greater area
before that force reaches the support layer. Hardened steel appears to
combine the desired hardness (up to a Mohs of almost 7) and flexibility.
Although lacking the hardness of steel, some organic polymers,
particularly engineering polyesters, have provided adequate support.
A ceramic/metallic laminate also possess the properties needed to resist
impact. Impact occurs when a heavy object strikes the floor. Damage is
most likely to occur when the pressure (that is force per unit area) is
large enough to cause an indentation. Here the tensile strength of the
steel should resist putting the ceramic in tension.
An additional property that the support layer should possess is the ability
to produce a gradual contour rather than an abrupt contour, both when a
grit particle exerts a force on it through the ceramic film and when it is
subjected to impact. Calculations nave shown that for a given vertical
displacement, a gradual contour subjects the ceramic film to less tension
than does the abrupt contour. In order to produce a gradual contour, the
support layer should be flexible but not limp. Two materials that possess
the desired properties are properly tempered spring steel and polyester
based sheet molding compounds.
The ceramic film should have hardness at least of about 6 Mohs and good
strength. To possess these attributes, the ceramic must have the proper
microstructure. In films formed by atomistic deposition, desirable
microstructure can be attained by increasing the temperature and the
bombardment energy. One of the advantages of using a steel support layer
is that a high enough temperature can be used to get optimum
microstructure.
The ceramic film should be applied so that it is under compression. This
can be accomplished by depositing the metal-atom portion of the ceramic
first and then adding the other element later, either in the same step or
in a second step. Using a two-step process allows better control for
deposition of the nonmetallic atoms.
The ceramic/metallic laminate is preferably adhered to a conformable
support layer. This support layer must be hard enough to support the
ceramic/ metallic laminate but must also be able to conform to any
irregularities in the subfloor. To perform in a superior manner, the
conformable support layer should be capable of inelastic deflection, i.e.,
capable of permanent deflection with or without residual forces such as
applied by adhesives.
In addition, if used in resilient sheet goods it must accommodate some
lateral movement of the subfloor. To be able to perform over all subfloors
including particleboard, the floor covering should have a rupture strain
in excess of 0.3%. Due to seasonal changes including temperature and
humidity, particleboard subfloors expand and contract about 0.3% during
the year. Plywood expands and contracts about 0.15%. Therefore, to perform
adequately over a wooden subfloor, the floor covering including the wear
layer should have a critical buckle strain of at least 0.1% and preferably
at least 0.3%. Floor coverings of the present invention having plastic
support structures meet this requirement.
The support layer preferably is typically made from an organic polymer. It
is desirable to select the polymer so that its viscoelastic character will
allow it to conform to the floor and still enable it to resist indentation
by a rapid impact.
Surface contours can readily be incorporated by embossing the metallic
substrate layer before application of the ceramic film. Incorporation of a
pattern could be done most readily by printing the pattern on the metallic
substrate before deposition of the ceramic film. Some of the ceramic films
that can be deposited atomistically are colored, and they may be applied
in patterns by use of stencils.
Although the focus of this invention is on atomistically deposited
ceramics, the concept of a thin flexible metallic substrate layer could be
used with other types of ceramics. Colored ceramic glazes or inks used in
conventional ceramic technology could be applied in a pattern on the
metallic substrate layer to form a wearlayer in place of the atomistically
deposited ceramic film.
The basic concept is combining thin, hard wear surfaces with decorative,
support structures to produce unique wear-resistant flexible flooring
products. The flooring products have the appearance retention
approximating that of ceramic tile but are light weight and easier to
install.
A series of inorganic oxides and nitrides (including aluminum oxide and
silicon oxide) has been used as the thin, hard inorganic wear layer. The
variety of materials used for the support layers include combinations of
metals, plastics, rubber and mineral/binder systems. The means of
decoration include glass frits, holograms, sublimable dyes and pigmented
inks. The plastics, rubber and mineral/binder systems may be through
color. Outstanding performance has been demonstrated in an embodiment
consisting of three microns aluminum oxide over ten microns glass
decorative layer on seven mils tempered steel shim stock bonded either to
a filled vinyl tile or a layer of rubber, and also in an embodiment
consisting of three microns of aluminum oxide over a sublimable ink
decorated polyester sheet molding compound (PSMC). Aluminum oxide coated
PSMC resists scratches better than any organic or organic/inorganic
coating tested.
Since each layer of the floor covering laminate affects performance, a
layer of rotogravure ink will change the appearance retention of a wear
layer on a plastic support. Therefore, inks, such as sublimable inks,
which will diffuse into the support layer are preferred.
The advantages of the flooring products of the present invention include an
appearance retention in traffic environments in a product which can be
light in weight, which can be either rigid or conformable, which can be
thinner than products currently in the market place, which can be
flexible, which can be more resilient than ceramic tile, and which can be
installed with conventional resilient-flooring tools.
One preferred embodiment of the floor covering 1 is shown in FIG. 1. The
support 2 is a metal, plastic, rubber or mineral/binder system. A wear
layer 3 of hard inorganic material is deposited on the support by a
reduced pressure environment technique. A decorative layer 4 is deposed
between the support layer and the wear layer. The preferred metal is
stainless steel. While such metals as ferroplate, brass/ferroplate,
steel/ferroplate, chromium-plated brass and 01 steel have been used, any
flexible but stiff support can be used.
The preferred thickness of the support is from about three to about nine
mil, most preferably about five to about seven mil. Two and four micron
alumina wear layers on three, five and seven mil tempered shim steel did
not crack even when the resulting laminate was supported by a deformable
rubber of Shore hardness 70 and walked on by women in high heels. The
three-mil substrate could be pierced by high heels.
The preferred Young's modulus is about 3.times.10.sup.7 lbs./inch.sup.2. A
modulus of this value or less ensures that the laminate is sufficiently
flexible to bend around a 2-inch mandrel without the wear layer cracking,
even when the wear layer is on the convex side. Preferably, the floor
covering is sufficiently flexible to bend around a 20-inch mandrel without
cracking.
The support substrate may also be a decorated or undecorated plastic,
rubber or mineral/binder system provided the support layer is sufficiently
rigid. The support layers tested include a polyester sheet molding
compound (PSMC), rigid polyvinylchloride (PVC) on a tile base,
polyethersulfone on a glass base, glass fiber reinforced polyester, fiber
filled phenolic, polyetheretherketone with and without a glass base,
polyimide on a glass base, polymethylmethacrylate, a photographic
polyester on a glass base, Teflon, and PVC on PSMC. A preferred polyester
support substrate material is PSMC or polyethylene terephthalate. A fiber
filled polyester is more stable and yields fewer cracks.
The thickness of the wear layer must be at least one micron. Preferably the
thickness of the wear layer is at least about three microns. Thickness of
less than three microns tend to fail more frequently.
Hardness of the wear layer equal to and preferably greater than that of
silica also is desirable. Preferably the hardness is at least 6 Mohs, and
more preferably 8.5 Mohs.
The invention includes wear layers of metal, metal oxides and metal
nitrides. The preferred compositions include Al.sub.2 O.sub.3, SiO.sub.x,
AlN, Si.sub.3 N.sub.4 and TiN. Flooring structures with five to eight
microns of Al.sub.2 O.sub.3 and SiO.sub.x supported on an undercoated,
reinforced polyester substrate had gloss retention superior to currently
marketed wear layer materials. Although individually visible scratches
were apparent, the scratches did not affect gloss retention. The scratches
can be eliminated or at least minimized by obtaining a good match between
the mechanical properties of the substrate and the wear layer. Gloss
retention and overall appearance retention is increased by increasing wear
layer hardness and substrate hardness. Therefore, Si.sub.3 N.sub.4 may be
a superior wear layer to Al.sub.2 O.sub.3.
The decorative layer 4 is a glass or ceramic frit, or pigment. The use of
printable inks enables the creation of intricate designs. However, since
the wear layer materials may be colored, the wear layer and decorative
layer may be combined and a multi-colored wear layer can be deposited with
a low pressure environment technique with the use of stencils.
The structure of the FIG. 1 embodiment is acceptable for a resilient
flooring structure which is rolled for storage and transport to the
installation site, provided the laminate is sufficiently flexible.
However, if the flooring structure is a 12.times.12 inch tile having a
rigid support structure, the tile may not be capable of conforming to the
irregularities of a wood subfloor and therefore may require installation
procedures similar to ceramic or marble.
To overcome this disadvantage the laminate may be bonded to a resilient or
conformable layer 5 as shown in FIG. 2. The conformable layer 5 has
dimensions slightly greater than the laminate. This allows for the
difference in thermal expansion between the subfloor and the laminate. The
conformable layer is capable of inelastic deflection under gravitational
forces so that over a reasonable length of time, the lower surfaces of the
laminate contacts the subfloor over substantially the entire surface area.
The conformable layer is capable of conforming to the contour of the
subfloor, including a 1/16" ledge between two plywood sheets forming the
subfloor.
The sharp corners of the FIG. 2 embodiment may cause problems since the
tiles cannot be laid in a perfectly flat plane. Therefore, the corners
tend to snag the soles of shoes. To avoid this problem, the tile may be
formed as shown in FIGS. 3 and 4. The laminate of support structure 2,
decorative layer 4 and wear layer 3 is formed. Then the laminate is press
molded into a cup-shape and bonded to the resilient support base 6. The
sides 7 of the laminate are substantially perpendicular to the plane of
the conformable layer and are adjacent the sides of the conformable layer.
In another embodiment shown in FIG. 5, the conformable layer 8 has
alignment marks 9 on the upper exposed surface. The tiles 1 are bonded to
the conformable layer in alignment with the marks to give a pleasing
decorative appearance and a discontinuous wear surface. The
discontinuities improve flexibility of the floor covering and may extend
down to a micron scale.
The following examples, while not intended to be exhaustive, illustrate the
practice of the invention. Procedure for the Preparation of Vapor
Deposited Coatings Coating Materials. Metals and metal oxides were
obtained in 99.9% nominal purity from standard industrial sources. Water
was removed from gases using molecular sieve traps. Al.sub.2 O.sub.3
(99.99%) and SiO.sub.2 (99.99%) were obtained from E. M. Industries;
ZrO.sub.2 (99.7%) and Ta.sub.2 O.sub.5 (99.8%) was obtained from Cerac,
Inc.; TiO.sub.2 (99.9%), was obtained from Pure Tech, Inc.
Apparatus.
The deposition system (Denton DV-SJ/26) included a 66 cm wide high vacuum
bell-jar assembly; a high speed pumping system (CTI Cryogenics CT-10
cryopump and Alcatel ZT 2033 mechanical pump); an electron-beam
vaporization source (Temescal STIH-270-2MB four-hearth "Supersource", with
an 8 kWatt Temescal CV-8 high-voltage controller and e-beam power supply
and Temescal XYS-8 sweep control); a resistively heated vaporization
source (Denton Vacuum, 4 kWatt); a cold cathode ionization source (Denton
Vacuum model CC101 with both CC101BPS and CC101PS biased and unbiased
power supplies); a residual gas analyzer (Inficon Quadrex 200); a quartz
crystal type deposition rate controller (Inficon IC6000); four eight inch
circular deposition targets affixed to a planetary rotation sub-system;
and a 10" diameter stainless steel aperture for focusing the e-beam (or
thermally) evaporated material and the ion plasma on the same deposition
surface. The various power supplies, pressure and gas flow monitors were
operated either automatically using Denton's customized process control
system, or manually. Typically, a deposition run began with an automated
pump-down process, was followed by a deposition process controlled by the
IC6000 and ended with an automated venting cycle.
Deposition Process.
The following general procedure was followed for all deposition runs.
Following evacuation to .ltoreq.1.0.times.10.sup.-5 Torr the temperature
of the chamber, as measured by a centered thermocouple at planet level,
was adjusted to the desired deposition temperature and the planetary
rotation was started. Next, Ar gas was admitted to increase the chamber
pressure to about 1.times.10.sup.-4 Torr, and a plasma 300-600
mAmps/300-600 Volts was initiated at the cold cathode source (current
density between 95 and 500 u-amps//cm.sup.2) which was used to
sputter-clean the substrates, in situ, for five minutes. The deposition
process was thereafter controlled by an IC6000 process which typically
included parameters such as heating rates and times, material densities,
desired deposition rates and thicknesses, and the number of layers
desired. Prior to deposition, the substrates were shielded from the metal,
or metal oxide source. Ion bombardment with an ion plasma began and the
shields were removed simultaneously when the IC6000 signaled that the
metal or metal oxide had been heated to the temperature appropriate for
vaporization. A quartz crystal microbalance provided input for the IC6000
feedback loop system which provided deposition rate control for the
remainder of the process. After deposition of a specified thickness, the
ion source was turned off, the shields replaced, and the vapor sources
allowed to cool.
Rupture Strain Test for Thin Ceramic Coatings
One surprising feature of the present invention is the rupture strain of
the thin hard inorganic coatings of the present invention. Obtaining the
rupture strain of a thin, hard inorganic film or coating such as a ceramic
is a difficult task as the coating is not thick enough to be
self-supporting to be tested with conventional apparatus. Among the
properties of yield stress, yield strain, modulus of elasticity, rupture
or ultimate strain and Poisson's ratio, the yield strain is of most
importance as the wear layer will undergo strain as determined by the
underlying load support structure. To create a support structure, it is
necessary to determine how much strain can be tolerated by the wear layer
and then make design adjustments of the support parameters so that this
strain will not be attained in service.
Ceramics are brittle and characteristically, the yield strain is close to,
and in a practical sense, is equal to the ultimate or rupture strain. A
ductile region does not exist between yield and rupture. This condition
makes the test more definitive as rupture is more readily detected than
yield, i.e., a crack is observed at the ultimate strain or rupture.
An evaluative test for measuring the ultimate strain to brittle fracture in
a thin ceramic film was developed. The test is parasitic in that it relies
on a host to produce the elongation strain in the ceramic coating. A thin,
highly tempered steel strip is coated with a very much thinner coating of
the wear layer (ratio of thicknesses of 250 to 1). The steel strip is bent
in a cantilever fashion and being so thick compared to the coating, its
bending performance is not affected by the presence of the coating. By
measuring the deflection of the cantilever, the surface strain of the bent
steel can be calculated by elastic mechanics equations. The coating will
experience the same elongation strain as the surface of the steel. The
beam is progressively deflected increasing the surface strain of the
steel. When the rupture strain of the coating is attained, the coating
ruptures by cracking which is visually evident. Measurement of the
deflection of the beam and the position along the beam where the crack
occurred are sufficient data to calculate the strain when the crack
occurred.
The credibility of the test is dependent upon the following items: (1) the
coating must be 100% and adhered to the cantilever surface, (2) the
deflection of the beam must be small to insure accuracy with use of
elastic beam formulae and (3) the yield strain of the cantilever beam must
be greater than the rupture strain of the coating.
The detection of a crack and its position must be accurately determined.
Detection of a crack in a three micron transparent film requires scrutiny.
Observance at 40.times. magnification and illumination by collimated light
appears to be necessary to discover the existence of a typical tension
crack.
FIG. 6 depicts the instrument setup to detect and measure the position of
the rupture cracks in the wear layer coating. The clamp 10 holds the
specimen 11- in a horizontal reference plane indicated by dashed line 12.
Micrometer 13 both deflects and measures the distance of deflection ye.
The cracks 14 in the wear layer 15 are observed with the aid of microscope
16 and collimated light source 17.
The length of the beam and its thickness are inter-related and wide
variations of the two are possible. A length of two inches and a thickness
of 0.030 inches has been found suitable for creating observable strain
cracking of the wear layer. The test procedure is also usable in
evaluating compressive surface strains by simply mounting the beam so that
the bending places the coating in compression, i.e., inverting. The unit
then deflects up, not down. The percent surface strain at position X, ex,
is calculated by the following formula:
##EQU1##
Test evaluation of the method and instrumentation was done on one half inch
wide specimens with a standard coating of 3 microns of Al.sub.2 O.sub.3.
Specimens 1 to 4 were coated by the procedure set forth above. A glass
decal was also fused to a 0.031 inch thick 302 stainless steel strip to
form Sample 5 which had a coating thickness of 10 microns.
Specific values of these coating operations are as follows:
______________________________________
Crack Observed
Length Thickness % Strain @ Rupture
Specimen
inch inch (Calculated)
______________________________________
1 1.75 0.030 0.60%
2 1.75 0.030 0.71%
3 2.50 0.024 0.56%
4 2.25 0.030 0.33%
5 2.50 0.031 >0.58%
______________________________________
Two factors that contribute to the high strain value are:
1. The coating is not a single crystal as it is deposited in a layer form
which builds in some form of voids. This is evidenced by repeated
measurements of deposit density of 160 lbs. per cubic ft. as contrasted to
247 lbs. per cubic ft. for single crystal sapphire. The coating structure
conceivably has more extensibility before rupture.
2. This test detects elongation strain-to-rupture on the
as-deposited-coating. The deposited coating may not and probably is not
residual-strain-free. Other sources of information and papers on
deposition cite conditions creating high compression or tension deposition
strains. If the coating is deposited with compressive strains, these
strains must be diminished to zero by bending before actual tension
strains are created. Thus if the coating were under compression from
deposition, this test would measure the sum of the residual compressive
strain plus the actual tension strain to failure.
Samples 1 to 4 present a range of as-deposited strain-to-rupture of 0.3 to
0.7%. The variation of strain of several samples from any one coating
operation has been experimentally found to be =0.1%. This suggests that
there were either variations in the coating structure or residual strains
in the samples tested.
Analysis of the cracking behavior and patterns discloses characteristics of
the coating. The observed cracking has been "instantaneous" which is
typical of a brittle ceramic so that one can conclude that cracks will
propagate once started. The cracks for these samples produced under
progressive deflection were all perpendicular to the generated tensile
stress, were all parallel, and were surprisingly uniformly spaced one from
the other. The spacing was small averaging four tenths of a mil apart.
This indicates a tightly bonded, uniform coating as no delamination
occurred and the cracking progressed in repetitive fashion.
The cracks in the samples 1 and 2 were evident in the deflected beam but
could not be observed (at 40.times.) when the beam was removed from the
instrument and returned to the flat condition. Having cracked and being a
ceramic, the cracks cannot heal to a once-again continuous surface. A
machinist's dye on the surface did not make the cracks visible. This
suggests that the cracks were pushed together tightly when the specimen
was returned to flat and that there was no debris thrown off from the
edges of the crack. It could be surmised that the coating was under
residual compression strains when deposited.
EXAMPLES 1-1 TO 1-36
The following are examples of hard inorganic materials which have been
deposited on various substrates:
TABLE 1
______________________________________
No. of
Example
Film Substrate Thickness
Film
No. Mat'l. Material (u) Layers
______________________________________
1-1 SiO.sub.2
SS.sup.1 foil 10.4 11
1-2 SiO.sub.2
SS foil 7.9 1
1-3 ZrO.sub.2
SS foil 2.5 1
1-4 Al.sub.2 O.sub.3
SS foil 0.5 1
1-5 Al.sub.2 O.sub.3
SS foil 1.5 2
1-6 ZrO.sub.2
SS foil 4.8 1
1-7 Al.sub.2 O.sub.3
SS foil 5.4 1
1-8 Al.sub.2 O.sub.3
Ferroplate 11.3 32
1-9 Al.sub.2 O.sub.3
Ferroplate 3.2 26
1-10 Al.sub.2 O.sub.3
Ferroplate 6.7 52
1-11 Al.sub.2 O.sub.3
Ferroplate <1.0 1
1-12 Al.sub.2 O.sub.3
Ceramic Tile 1.0 1
1-13 Al.sub.2 O.sub.3
Ceramic Tile 32
1-14 Al.sub.2 O.sub.3
Brass Ferroplate
1.0 1
1-15 Al.sub.2 O.sub.3
Brass Ferroplate 20
1-16 Al.sub.2 O.sub.3
Brass/Ferroplate 29
1-17 Al.sub.2 O.sub.3
Steel/Ferroplate 1
1-18 Al.sub.2 O.sub.3
Steel/Ferroplate 20
1-19 Al.sub. 2 O.sub.3
Steel/Ferroplate 29
1-20 Al.sub.2 O.sub.3
1/8" Thick 01 Steel 1
1-21 Al.sub.2 O.sub.3
1/8" Thick 01 Steel 29
1-22 Al.sub.2 O.sub.3
1/8" Thick 01 Steel 32
1-23 Al.sub.2 O.sub.3
TEOS.sup.2 /Ceramic Tile
0.1 1
1-24 Al.sub.2 O.sub.3
TEOS/Ceramic Tile
0.2 1
1-25 Al.sub.2 O.sub.3
TEOS/Ceramic Tile
0.5 10
1-26 ZrO.sub.2 on
Ferrosteel 0.1 1
Al.sub.2 O.sub.3
1-27 Al.sub.2 O.sub.3
Ceramic Tile 1.2 3
1-28 Al.sub.2 O.sub.3
Brass Ferroplate
1.2 3
1-29 Al.sub.2 O.sub.3
Brass Ferroplate
1.0 1
1-30 TiN.sub.x
Ferro Steel 0.3 1
1-31 TiN.sub.x
Ferro Steel 1.0 1
1-32 TiN.sub.x
Ferro Steel 1.9 1
1-33 SiO.sub.2
Ferro Steel 1.1 1
1-34 Al.sub.2 O.sub.3
Marble 3.0 1
1-35 TiN.sub.x
Marble 2.4 1
1-36 TiN.sub.x on
Marble 1/3 2
Al.sub.2 O.sub.3
______________________________________
.sup.1 Stainless Steel
.sup.2 Tetraethylorthosilicate
Samples approximately six inches square were tested in the Walkers Test in
which six female walkers reached a total traffic count of 1200.
On matte finish, hard (manufacturer's ratings of Mohs 6.5 and 8.5) ceramic
tiles, aluminum oxide coating did not scratch to a significant extent.
Increased damage occurred in samples where the aluminum oxide was
deposited onto ceramic substrates with Mohs hardness less than 6.5.
On hard, shiny ceramic tile, aluminum oxide performed well. On softer,
unglazed tile, the coating appeared to provide protection against large
scratches during the first half of the test, and at the end of the test
there were fewer (but noticeable) scratches on the coated than on the
uncoated samples. The aluminum oxide coating prevents the formation of
haze (multiple fine scratches) on brass ferroplate. On ferroplate,
application of aluminum oxide at 140.degree. C. produced a coating that
performed as well as one applied at 250.degree. C. The best ferroplate
samples were ones coated when other types of samples were not in the
chamber.
When aluminum oxide was applied to a shiny ceramic tile that was
essentially not scratched in its uncoated state (and on which scratches,
if present, could be readily seen), the coating performed almost as well
as the uncoated tile. The coated tile had two fairly large, almost
scuff-like scratches but otherwise was essentially as good as the uncoated
tile.
Under the same test conditions, the coated ferroplate samples--although
exhibiting complete resistance to multiple fine scratches--had a number of
large scratches on them. The ferroplate samples with the most scratches
were those prepared at the same time as samples other than ferroplate.
These results hint that the coating may be adversely affected by
contaminants from the other samples.
On softer, unglazed tile, the coating appeared to protect the tile from
large scratches during the first half of the test. At the end of the test,
there were fewer but more noticeable scratches on the coated, with coating
removed along the scratches.
EXAMPLES 2-1 TO 2-8
Performance of vapor-deposited aluminum oxide was evaluated using the
Walker Test. Under these test conditions, the aluminum-oxide-coated
ferroplate samples with the thicker coatings were the best performing
flooring prototypes. The only samples to retain their gloss in all areas
were those with vapor-deposited aluminum oxide coatings at least 2.5
microns thick on ferroplate. The principal damage to these samples
consisted of medium and large scratches.
Samples approximately six inches square were tested in the Walkers Test in
which six female walkers reached a total traffic count of 1236.
Because the samples were only six inches square, the walkers either placed
a single foot on each sample or had to make a special effort to place both
feet on each sample. It was observed that when they placed both feet on a
sample, they usually placed their feet on diagonally opposite quadrants of
the sample. This produced on most samples two areas which were much more
worn than other areas. See results in Table 2.
TABLE 2
__________________________________________________________________________
Example
Support
Wear
No. of
Al.sub.2 O.sub.3 ThK.
No. Substrate
Layer
Layers
Total, u
Comments
__________________________________________________________________________
2-1 Brass Al.sub.2 O.sub.3
1 0.3 Purple-blue color; many
Ferroplate fine scratches and very
dull sections throughout
sample; Al.sub.2 O.sub.3 appeared
to be removed by traffic
in 2 quadrants
2-2 Brass Al.sub.2 O.sub.3
1 0.5 Green to colorless; some
Ferroplate fine scratches, some
larger scratches, no
dull areas Al.sub.2 O.sub.3 appears
to be intact
2-3 Brass Al.sub.2 O.sub.3
1 1.0 Pink to colorless; many
Ferroplate fine scratches, Al.sub.2 O.sub.3
partly removed
(uniformly)
2-4 Brass Al.sub.2 O.sub.3
5 2.0 Some fine scratches,
Ferroplate most damage was large-
sized scratches; good
gloss retention
2-5 Brass Al.sub.2 O.sub.3
2 2.0 More fine scratches than
Ferroplate 2-4; some large size
scratch damage
2-6 Brass Al.sub.2 O.sub.3
1 3.2 Almost no fine
Ferroplate scratches, some large
size scratches
2-7 Brass Al.sub.2 O.sub.3
-- 2.5 Almost no fine
Ferroplate scratches, all damage
2-8 Brass Al.sub.2 O.sub.3
1 3.2 medium to large
Ferroplate scratches
__________________________________________________________________________
The performance of aluminum-oxide-coated ferroplate with a coating at least
2.5 microns thick was superior to commercial wear layers. The only samples
to retain their gloss in all the pivot areas were those with aluminum
oxide coatings at least 2.5 microns thick on ferroplate. The principal
damage to these samples consisted of a number of medium and large
scratches, each one of which is individually visible.
Indentations produced by spike heels on the aluminum-oxide-coated
ferroplate did not cause macrocracking. Small parallel cracks were formed
in the indentation but do not extend appreciably beyond the indentation.
EXAMPLE 3
In this example, use of an ion gun during Al.sub.2 O.sub.3 deposition did
not significantly affect gloss retention--for these flooring structures.
Use/nonuse of the ion gun during Al.sub.2 O.sub.3 depositions on ceramic
decal/steel substrates generally has no significant effect on Walker Test
performance.
The performance level of the Al.sub.2 O.sub.3 coated ceramic decal
decorated steel structures was limited by the spalling of the ceramic
decal at its interface with the steel support. Three-layer ceramic decal
samples on 7-mil steel had fewer scratches than the coated single layer
ceramic decal/steel samples. The triple-decal samples were more severely
marred due to their greater tendency toward spalling.
Samples approximately six inches square were tested in the Walkers Test.
Table 3 lists average gloss readings.
Al.sub.2 O.sub.3 wear layers were evaporated by the e-beam gun without the
use of crucible liners. The chamber was baked out at 250.degree. C. for 1
to 3 hours prior to each deposition to minimize water vapor contamination.
The substrate temperature was allowed to "float" starting at
30.degree.-90.degree. C. during the deposition runs. For depositing done
without the ion gun an O.sub.2 atmosphere of approximately
2.3.times.10.sup.-4 Torr was maintained.
The Decal used was #A2894 with ceramic overglaze colors, obtained from
Philadelphia Decal. The steel was 7 mil stainless steel, obtained from
Lyon Industries.
TABLE 3
__________________________________________________________________________
Single Decal
Single Decal
Triple Decal
Triple Decal
No. of
Ion Gun No Ion Gun
Ion Gun No Ion Gun
Passes
Initial
Final
Initial
Final
Initial
Final
Initial
Final
__________________________________________________________________________
0 -- 81.3
-- 81.1
-- 96.6
-- 96.9
24 84.5
75.8
83.4
72.3
97.1
92.3
99.4
93.5
48 84.1
83.8
81.6
78.6
96.4
96.0
96.4
97.8
102 79.0
77.2
82.3
82.7
96.0
97.9
94.7
95.1
204 85.2
83.4
83.1
83.2
97.9
97.2
95.9
95.4
402 75.1
76.8
75.9
73.9
94.5
88.4
95.8
95.0
804 80.5
79.9
80.0
78.8
95.8
98.7
96.4
91.3
1200
80.5
81.0
81.4
76.6
98.2
88.3
100.0
91.6
__________________________________________________________________________
EXAMPLES 4-1 TO 4-23
Evaluations were made of (a) alumina on a stiff but flexible substrate, (b)
coatings prepared with and without the ion gun, and (c) layered coatings.
Alumina (2-4 microns) on a flexible but stiff substrate (3-, 5-, or 7-mil
tempered steel) did not crack in the Walkers Test when (1) the resulting
laminate was supported by a deformable rubber (Shore hardness 70) and (2)
even when high heels were included in the Walkers Test. The laminate
resisted fine scratches, in a manner similar to ferroplate tested earlier,
but the severity of individually visible scratches was accentuated by
failure of adhesion. The failure was not, however, between the substrate
and coating but rather between the substrate and a purplish layer that was
formed on the substrate.
The performance in the Walkers Test of alumina on ferroplate was greatly
improved by use of the ion gun during deposition.
The standard, single-layer, alumina coating retained its appearance better
than any of the layered coatings. The 18-layer chromium/alumina coating
was a brilliant magenta.
In Table 4 are listed the substrates and comments on the appearance of the
samples after trafficking.
TABLE 4
__________________________________________________________________________
Total
Thickness
Example Support
Film No. of
(SEM,
No. Substrate
Layer
Material
Layers
microns)
Comments
__________________________________________________________________________
Control
5-mil Shim
Silicone
Uncoated Matted. A number
4-1 Rubber of individual
scratches. A few
heel dents.
Control
7-mil Shim
Silicone
Uncoated Matted. A number
4-2 Rubber of individual
scratcnes. No
heel dents.
Control
5-mil Shim
Tile Uncoated Similar to above
4-3 5-mil control.
Control
7-mil Shim
Tile Uncoated Similar to above
4-4 7-mil control.
4-1 3-mil Shim
Silicone
Al.sub.2 O.sub.3
1 4.0 Two-piece sample.
Stock Rubber No matting. A
number of indivi-
dual scratches.
Some delamination
along center seam.
Scratches accentu-
ated by adhesive
failure. One heel
penetration.
4-2 5-mil Shim
Silicone
Al.sub.2 O.sub.3
1 4.0 No delamination.
Stock Rubber No matting. Much
less scratching
than Example 4-1.
Only a few barely
discernible heel
dents. Scratches
accentuated by
adhesive failure.
4-3 7-mil Shim
Silicone
Al.sub.2 O.sub.3
1 4.0 No delamination.
Stock Rubber No matting. Fewer
scratches than
Example 4-2. No
discernible heel
dents.
4-4 Steel Tile Al.sub.2 O.sub.3
1 4.0 No matting. A
Ferro number of heel
dents. Number of
scratches less
than Example 4-2
but more than
Example 4-1.
4-5 3-mil Shim
Silicone
Al.sub.2 O.sub.3
1 4.1 Two-piece sample.
Stock Rubber No matting. No
delamination.
Slightly fewer
scratches than
Example 4-2.
Scratches accentu-
ated by adhesive
failure. A number
of heel dents.
4-6 5-mil Shim
Silicone
Al.sub.2 O.sub.3
1 4.1 Similar to Example
Stock Rubber 4-2.
4-7 7-mil Shim
Silicone
Al.sub.2 O.sub.3
1 4.1 No matting, no de-
Stock Rubber lamination. Many
scratches which
are accentuated by
adhesive failure.
4-8 Steel Tile Al.sub.2 O.sub.3
1 4.1 Similar to Example
Ferro 4-4.
4-9 3-mil Shim
Tile Al.sub.2 O.sub.3
1 2.1 No matting.
Stock Slight delamina-
tion at multiple
scratches. Signi-
ficantly more
scratches than
Example 4-5.
Scratches accentu-
ated by adhesive
failure.
4-10 5-mil Shim
Tile Al.sub.2 O.sub.3
1 2.1 Similar to Example
Stock 4-6, but slightly
fewer scratches.
4-11 7-mil Shim
Tile Al.sub.2 O.sub.3
1 2.1 No matting, no de-
Stock lamination. Few-
est scratches of
any shim stock
sample. Scratches
accentuated by
adhesive failure.
4-12 Steel Tile Al.sub.2 O.sub.3
1 2.1 Similar to Example
Ferro 4-4.
4-13 3-mil Shim
Tile Al.sub.2 O.sub.3
1 3.1 No matting, some
Stock delamination.
Second most
scratches.
4-14 5-mil Shim
Tile Al.sub.2 O.sub.3
1 3.1 Most scratches of
Stock any shim stock
sample
4-15 7-mil Shim
Tile Al.sub.2 O.sub.3
1 3.1 More scratches
Stock than Example 4-11.
4-16 Steel Tile Al.sub.2 O.sub.3
1 3.1 Similar to
Ferro Example 4-4.
4-17 Steel Tile Al.sub.2 O.sub.3
1 3.0 Similar to
Ferro Example 4-4.
4-18 Steel Tile Al.sub.2 O.sub.3
1 3.0 Similar to
Ferro Example 4-4.
4-19 Steel Tile Al.sub.2 O.sub.3
1 3.0 Large areas delam-
Ferro inated (before
test). Delamina-
tion along
scratches.
4-20 Steel Tile SiO/Al.sub.2 O.sub.3
5/5 2.0 Some matting, many
Ferro scratches.
4-21 Steel Tile SiO/Al.sub.2 O.sub.3
5/5 2.0 No matting but
Ferro many deep
scratches.
4-22 Steel Tile Cr/Al.sub.2 O.sub.3
9/9 5 Magenta. Worn
Ferro thru on a pivot
point. Delamina-
tion around pivot
point.
4-23 Steel Tile Al/Al.sub.2 O.sub.3
3/3 1.5 Matted areas.
Ferro Many scratches in-
cluding very fine
scratches.
__________________________________________________________________________
The Al.sub.2 O.sub.3 metallic laminate was sufficiently flexible that it
could be bent around a 2-inch mandrel without the Al.sub.2 O.sub.3
cracking, even when the Al.sub.2 O.sub.3 was on the convex side. The
optimum thickness of the substrate layer appears to be 5 to 7 mils; the
3-mil substrate could be pierced by high heels.
The alumina prevented the formation of fine scratches on the shim steel.
The severity of individually visible scratches was accentuated on the
coated samples by adhesive failure.
The use of the ion gun during deposition improved the performance of
alumina on ferroplate. The sample prepared without the ion gun had many
more scratches, significant adhesion failure along the scratches, and an
area about 1.times.21/2 inches that delaminated before the test.
The 18-layer chromium/alumina coating was a brilliant magenta. The coating
was 5 microns thick, so this situation was different than one in which
thin coatings exhibit interference patterns.
The standard coating retained its appearance better than any of the layered
coatings (Examples 4-20 to 4-23).
EXAMPLES 5-1 TO 5-15
Outgassing during the deposition process was demonstrated to adversely
effect the scratch performance Al.sub.2 O.sub.3 thin films. The outgassing
species was tentatively identified as water. This problem may be
eliminated by addition of a high temperature bake-out cycle to the
deposition procedure. Outgassing was shown to affect the scratch
performance, and may greatly reduce scratch resistance.
For Al.sub.2 O.sub.3 deposition, a 3-hour plateau style bakeout at
250.degree. C. suppressed the outgassing sufficiently to prepare films
which had reproducible scratch resistance. In the absence of a bakeout,
severe outgassing occurred which adversely affected scratch resistance in
the Al.sub.2 O.sub.3 films produced. The outgassing was probably due to
thermal desorption of water from Al.sub.2 O.sub.3 on the walls of the
deposition chamber. Direct identification of the outgassing material must
await installation of a pressure adapter for the Residual Gas Analyzer. If
the bakeout is not feasible due to thermal limitations of the substrate
material, then the chamber should be freshly cleaned and lined with new
aluminum foil immediately prior to deposition on that substrate.
When the Al.sub.2 O.sub.3 coated glass substrates from deposition SERIES A
(See Table 1) were evaluated in the diamond stylus scratch test, two major
observations were noted: both the Load to Incipient Damage (LID), and the
type of damage at the LID changed from the first member of the series to
the last. The changes were not monotonic from the beginning of the series
to the end. For example, the first member of the series (Specimen 10) gave
a LID of 50 g due to the appearance of birefringeance along the scratch
track made by the diamond in the surface of the alumina. Scratching at
loads of up to 95 g showed an increase in the birefringeance, but at no
point was any film delamination observed. In contrast, for the second
member of the series, birefringeance occurred at an LID of 40 g; at 50 g
film delamination began and cracks appeared normal to the scratch
direction; and at 70 grams chipping was observed. For the third member of
the series, delamination and cracking were both observed at an LID of only
25 g, and film decohesion occurred at 40 g. The remaining members of the
series were also characterized by low LID's due to delamination, cracking
and film decohesion. These observations exemplify a progressive decrease
in adhesion between the vapor deposited Al.sub.2 O.sub.3 and the glass
substrates.
TABLE 5
______________________________________
Film Data, Physical and Mechanical Properties
______________________________________
SERIES A:
Example 5-1 5-2 5-3 5-4 5-5 5-6 5-7 5-8
Number
LID.sup.a (grams)
50 40 25 30 15 20 15 20
Thickness.sup.c
3.17 3.74 3.55 4.03 3.89 4.03 4.22 3.70
(.mu.)
Wt. Dep. 15.0 17.3 16.1 1.85 1.68 1.69 1.69 1.64
(mg)
SERIES B:
Example Number
5-9 5-10 5-11
LID.sup.a (grams)
45 40 45
Thickness.sup.c (.mu.)
3.31 2.98 3.31
SERIES C:
Example Number
5-12 5-13 5-14 5-15
LID.sup.a (grams)
50 45 45 45
Thickness.sup.c (.mu.)
4.08 3.65 3.70 3.50
______________________________________
.sup.a Load to Incipient Damage: Damage in excess of simple indentation
.sup.b Calculated, based on SEM thickness and a coated area of 16.75
cm.sup.2
.sup.c Obtained by Scanning Electron Microscopy
SERIES A
Eight consecutive deposition runs were performed. In each case, substrates
in addition to glass substrates were present in the chamber. These
substrates included Ferrosteel, 5 mil spring steel, chromed spring steel,
thick "01" steel plate (both chromed and untreated), stainless steel, and
several engineering plastics. In all but two of the runs in this series,
the samples were loaded into the deposition chamber in late afternoon of
the working day before the run. For the Examples 5-5 and 5-7, however, the
samples were loaded into the deposition chamber in the morning and the
system was allowed to pump down over the lunch hour.
SERIES B
Three consecutive deposition runs were performed. These runs contained only
glass substrates. The procedure was the same as that for SERIES A except
that Example 5-11 was subjected to a three hour bakeout cycle at
250.degree. C. while pumping overnight.
SERIES C
Four consecutive deposition runs were performed. These runs contained
additional substrates capable of withstanding a 250.degree. C. heat
treatment. For each of these runs the procedure included an overnight
bakeout at 250.degree. C.
Diamond stylus scratch test results are reported here as Load to Incipient
Damage (LID) to the nearest five grams of stylus weight loading. Because
the mechanism of scratching hard inorganic materials does not include any
macroscopically observable "recovery" mechanism, Load to Incipient Damage
is defined as that weight loading, in the LOM equipped with a 45.times.
objective, where damage other than a simple indentation is observed. For
example: the LID may be due to the observation of birefringeance at the
edge of the scratch track, by delamination of the film, chipping, or the
development of cracks.
Density measurements were obtained by dividing the weight gain of a
Ferrosteel slide by the area exposed for deposition (16.75 cm.sup.2) and
the film thickness as determined by SEM. Control experiments showed that
there was no detectable weight loss due to sputtering even after 20
minutes exposure to a 600 mA/600 V Ar+ ion plasma. In addition, a
Ferrosteel slide subjected to the entire deposition cycle but shielded
from deposition experienced no detectable weight change.
A clue into the cause of these adhesive differences was offered by a
qualitative comparison of Ion Gun voltage during the first few moments of
several of the SERIES A deposition runs. A high bombardment voltage was
attained immediately at the start of the deposition run and the voltage
was sustained throughout the run. However, voltage dropped at the onset of
deposition, and progressively longer times were required to reach and
sustain an ion voltage of 600 volts. Two important facts are associated
with this observation. First, the ion gun voltage is inversely
proportional to the chamber pressure. Thus a voltage drop is accompanied
by a pressure surge. Second, Al.sub.2 O.sub.3 films prepared using a high
voltage ion assist outperform those prepared with no ion assist.
Therefore, a pressure surge accompanied by a voltage drop will adversely
effect the wear performance of such a film.
The progressive nature of the deterioration in LID performance suggested an
impurity buildup as a function of chamber use. Thus it was proposed that
excess alumina deposited on the chamber walls gettered water vapor from
the laboratory atmosphere whenever the chamber was opened to install or
remove substrates. Aluminum oxide is a well known desiccant which is
activated by heat treatment in a vacuum. Radiation from the e-beam
evaporation source probably "activated" alumina which had accumulated on
the chamber walls during previous runs and caused the observed pressure
surges. Direct verification of this hypothesis using the Residual Gas
Analyzer (RGA) was not possible because of its pressure limitation.
The first indirect confirmation that water vapor was being desorbed was
obtained using the RGA under predeposition conditions. The RGA, upon
evacuation of the chamber to a pressure of 10.sup.-6 Torr showed a
constant (uncalibrated) water vapor pressure of 5.times.10.sup.-5 Torr.
When the quartz heaters in the chamber were energized, however, an
immediate pressure surge due to an increase in water vapor pressure was
observed. Unfortunately, the cutoff pressure for the RGA is 10.sup.-4
Torr, which is the vapor pressure in the chamber during most deposition
runs. Therefore, the RGA cannot be used during the runs to directly
confirm the water vapor hypothesis.
A second indirect confirmation of the role of water vapor during the
deposition process was obtained by examination of the scratch test results
obtained from deposition SERIES B (see Table 5). The first two depositions
in this series were run on consecutive days, under the same conditions as
the first two members of SERIES A. For the first two deposition runs in
both SERIES A and SERIES B, trends showing a decrease in scratch LID, and
an increase in voltage stabilization time was observed (the magnitude of
the pressure surge was mitigated by the chamber operator decreasing the
flow rate through the ion gun). Addition of a bakeout cycle to the
deposition procedure for the third deposition run in SERIES B resulted in
recovery of the scratch behavior observed in the first members of both
SERIES A and B, and decreased the time required to obtain a stable ion gun
voltage.
SERIES C was run in order to test the reproducibility of scratch tests
obtained from runs which included the bakeout cycle. In contrast to SERIES
A, no significant change in scratch performance from the beginning of
SERIES C to the end was observed.
The early moments of the deposition runs in SERIES C were not accompanied
by the voltage drops and pressure surges that were observed in SERIES A.
Also no change was shown in the type of scratch damage observed at the
LID.
EXAMPLES 6-1 TO 6-14
Increasing the thickness of the decorative layer improved the performance
of the glass and ceramic decals, both coated and uncoated except that of
the 20-micron thick glass decorative layers. Coating the decorative layer
with aluminum oxide improved the overall appearance retention in all
cases. The failure mode for the glass and ceramic decals appears to be
different. Diamond stylus scratch tests show that the glass decorative
layer crumbles under relatively high stylus load where the ceramic
decorative layer chips.
In previous Walkers Tests, the decorative layer which consisted of
5-micron-thick glass decals, showed large individually discernible
scratches that broke through to the metal substrate. Since the decorative
layer also supports the aluminum oxide layer a thicker glass layer should
provide better support. Samples made by layering glass decals were run in
the Walkers Test to test this idea.
The glass-ink decal has a nano-hardness of 6 Gpa. The best aluminum oxide
has a nano-hardness of 10 Gpa. There exist ceramic inks which form harder
decorative layers than the glass inks. These ceramic inks have a
nano-hardness value of 11 Gpa. Decals made from these ceramic inks not
only should provide better support for the aluminum oxide layer but
conceivably could act as a wear layer itself. Single and multiple layer
samples were prepared to evaluate the effect of thickness on performance.
Samples approximately six inches square were tested in the Walkers Test.
The samples were supported by a vinyl base tile to which they were
attached by adhesive transfer tape. Six walkers reached a total traffic
count of 1200.
Before and after trafficking, sixty-degree gloss measurements were made
with the Mallinckrodt Glossmeter. A measurement was made at the center and
at the center of each of four quadrants of the sample for a total of five
measurements.
Sample descriptions and gloss values are listed in Table 6. The glass
decals were 5 microns thick. The ceramic decals were 10 microns thick.
TABLE 6
______________________________________
Sample Gloss Values
No. Sample Descriptions Initial Final
______________________________________
6-1 1 layer glass decal/7 mil 302 steel
70 60
6-2 Aluminum oxide coated 1 layer glass
53 54
decal/7 mil 302
6-3 2 layer glass decal/7 mil 302 steel
96 70
6-4 Aluminum oxide coated 2 layer glass
63 59
decal/7 mil 302
6-5 3 layer glass decal/7 mil 302 steel
110 86
6-6 Aluminum oxide coated 3 layer glass
86 85
decal/7 mil 302
6-7 4 layer glass decal/7 mil 302 steel
83 37
6-8 Aluminum oxide coated 4 layer glass
73 58
decal/7 mil 302
6-9 1 layer ceramic decal/7 mil 302 steel
78 67
6-10 Aluminum oxide coated 1 layer ceramic
78 72
decal/7 mil 302
6-11 2 layer ceramic decal/7 mil 302 steel
87 84
6-12 Aluminum oxide coated 2 layer ceramic
90 90
decal/7 mil 302
6-13 3 layer ceramic decal/7 mil 302 steel
89 80
6-14 Aluminum oxide coated 3 layer ceramic
92 91
decal/7 mil 302
______________________________________
Increasing the thickness of the decorative layer improved the performance
of the glass and ceramic decals, both coated and uncoated. The sample with
the best appearance and gloss retention was the aluminum oxide-coated
triple-layer (30 micron) ceramic-decal sample. In general, the multilayer
ceramic decals resisted large scratches better than the multilayer glass
decals.
Coating the decorative layer with aluminum oxide improved the overall
appearance and gloss retention in all cases except that of the 5- and
10-micron thick glass decorative layers. The aluminum oxide coating
improved the gloss retention of both systems, with the coated ceramic
decal having the best gloss retention. On the ceramic decals, the aluminum
oxide reduced the number of large scratches. On the glass decals, the
aluminum oxide reduced the number of small scratches. With the ceramic
decals, some of the scratches appeared confined to the aluminum oxide
coating.
The ceramic decals appeared to adhere less well to the steel than did the
glass decals. At 10 microns, the ceramic decals resisted fine scratches
better than the glass decals but had more scratches to the metal. At 20
microns, the ceramic decals resisted both fine and large scratches better
than the glass decals but still had more scratches to the metal. The
chipping around the area of the scratches in the ceramic decals, seems to
indicate an adhesion failure, possibly due to differences in the
coefficient of thermal expansion.
The failure mode for the glass and ceramic decals appeared to be different.
Diamond stylus scratch tests on the same samples that made up this Walkers
Test showed that at relatively high loads (60-95 grams), the glass decals
tended to crumble where the ceramic decals did not. The crumbling decal
left granules of material on either side of the scratch. In the
multi-layer ceramic decal samples any failure noted could be described as
a chipping failure. The scratch from the stylus looked similar to aluminum
oxide scratches but had intermittent areas where the ceramic ink chips
away from the rest of the coating. It appeared that the ceramic ink in the
decorative layer had a greater inherent strength than the glass ink.
However, when stressed to the point of failure, the ceramic ink exhibited
a brittle failure where the glass crumbled.
EXAMPLES 7-1 TO 7-8
Addition of a ceramic primer to the composite structure eliminated the
spalling of the decorative layer seen in previous walker testing. Damage
was limited to large, individually visible scratches and can be grouped
into three types: (a) damage to the Al.sub.2 O.sub.3 layer only; (b)
damage to the decorative layer; and (c) damage to the metal substrate.
There was no deglossing due to fine scratches. The two ceramic primers
performed equally well.
Samples were tested in the Walkers Test. Table 7 lists the sample data and
the gloss values as measured. Two ceramic/metal composite categories were
tested. They were: (1) Al.sub.2 O.sub.3 -coated ceramic decal on H34001
primer on 7 mil 302 steel; and (2) Al.sub.2 O.sub.3 -coated ceramic decal
on J-M600001 primer on 7 mil 302 steel.
TABLE 7
______________________________________
Al.sub.2 O.sub.3
Sample
Thk..sup.3
Walker 60.degree. Gloss
Description No. (micron) Cycles
Initial
Final
______________________________________
Al.sub.2 O.sub.3 /Ceramic
7-1 4.8.sup. 400 89.4 81.0
Decal/ 7-2 4.8.sup. 800 88.8 79.3
H34001 Primer.sup.1
7-3 4.8.sup. 1200 86.1 84.4
7-4 3.8.sup.3
1200 85.6 80.8
Al.sub.2 O.sub.3 /Ceramic
7-5 4.3.sup.4
400 98.2 91.9
Decal/ 7-6 3.8.sup.3
800 94.2 90.1
J-M600001 Primer.sup.2
7-7 4.3.sup.4
1200 97.5 90.0
7-8 4.3.sup.4
1200 95.6 89.7
______________________________________
.sup.1 Manufactured by Heraeus, Inc.
.sup.2 Manufactured by Johnson Matthey
.sup.3 Light optical microscope thickness determination.
.sup.4 Average of four SEM measurements.
EXAMPLES 8-1 TO 8-19
Uncoated and Al.sub.2 O.sub.3 -coated, 30 micron thick decorative layer
samples had the very good appearance retention. Al.sub.2 O.sub.3 -coated
white H34002 primer (30 micron) samples were marginally better than the
30-micron, white H34002 primer samples. Al.sub.2 O.sub.3 -coated 10-micron
ceramic decal on 20 micron of white H34002 primer contained no scratches
to the metal substrate.
Six-inch square samples were tested in the Walkers Test. Table 13 shows the
sample descriptions and gives the raw data.
Three categories of wear layers were prepared.
1. 30 micron-H34002 primer on 7-mil 302-steel.
2. Al.sub.2 O.sub.3 -coated, 30 micron-H34002 primer on 7-mil 302-steel.
3. Al.sub.2 O.sub.3 -coated, 10 micron-ceramic decal on 20 micron-H34002
primer on 7-mil 302-steel.
All samples tested had fewer scratches to the metal. As previously seen,
the presence of the primer coat had eliminated spalling of the ceramic
layer from the damage area. The damage of the Al.sub.2 O.sub.3 -coated
decal samples was limited to the aluminum oxide layer and the decal only.
TABLE 8
______________________________________
Al.sub.2 O.sub.3
Example
Thk. Walker 60.degree. Gloss
Description
No. (Micron) Cycles
Initial
Final
______________________________________
30 Micron H34002
8-1 -- 200 89.9 95.5
Primer 8-2 -- 400 90.8 93.8
8-3 -- 800 94.7 91.9
8-4 -- 1200 94.1 92.3
8-5 -- 1200 92.2 91.6
8-6 -- 1200 94.4 93.7
8-7 -- 1200 93.3 90.8
Al.sub.2 O.sub.3/ 30 Micron
8-8 5.1 200 103.6 105.7
H34002 Primer
8-9 5.1 400 102.0 108.1
8-10 5.1 800 100.1 103.3
8-11 5.1 1200 99.1 102.4
8-12 4.8 1200 103.3 106.9
8-13 4.8 1200 102.6 105.6
8-14 4.8 1200 101.2 105.5
8-15 4.8 1200 101.5 102.7
Al.sub.2 O.sub.3 /Ceramic
8-16 4.6 200 87.6 96.2
Decal/20 Micron
8-17 4.6 400 85.8 94.0
H34002 Primer
8-18 4.6 800 90.9 92.7
8-19 4.6 1200 89.6 94.5
______________________________________
EXAMPLES 9-1 TO 9-41
Structures were fabricated using Ion Assisted Physical Vapor Deposition
(IAPVD) to deposit Al.sub.2 O.sub.3 or SiO.sub.x "ceramic" wear layers
onto undecorated plastic substrates. These structures had the same average
gloss retention profile as ceramic tile. Scratch and Walkers Tests
demonstrated the synergistic relationship between the coating and
substrate properties in these composites. Nanoindentation showed
relationships between hardness, chemistry and the processes used to
prepare the wear layers.
Flooring structures with 5-8 microns of Al.sub.2 O.sub.3 or SiO.sub.x
supported by an undercoated, reinforced polyester substrate have gloss
retention superior to currently marketed wear layer materials. However,
individually visible scratches were apparent in these structures. Although
these scratches did not affect gloss retention, the post-trafficking
appearance of the coated structures would be improved if all scratches
were prevented. The key to that prevention lies in obtaining a good match
between the mechanical properties of the plastic substrate and the hard
wear layer. In these examples, the aluminum oxide coating provided only
limited improvement to the performance of any organic-containing substrate
where adhesion failure (aluminum oxide removal) was a major factor.
Diamond stylus scratch testing and nonoindentation were the two main
characterization tests to monitor mechanical property response for the
title structures. The Al.sub.2 O.sub.3 and SiO.sub.x supported by
polyester sheet molding compound (PSMC) show the highest stylus LSP (Load
to Substrate Penetration), which is consistent with the superior gloss
performance of such structures. Nonoindentation results show that Al.sub.2
O.sub.3 is the hardest wear layer material tested in an actual flooring
prototype in which a plastic support was employed. Si.sub.3 N.sub.4 is
suggested as an alternative material.
Ion Assisted Physical Vapor Deposition (IAPVD) was used to produce films
for wear layers on plastic substrates. Metal or metal oxide vapor was
evaporated by heating with an electron beam until it vaporized. When the
vapor deposited on a substrate, simultaneous bombardment by an ion beam
helped to form a dense, defect free film. Materials deposited onto plastic
substrates include Al.sub.2 O.sub.3, SiO.sub.x, AL.sub.2 O.sub.3
-SiO.sub.x, and SnO.sub.x -SiO.sub.x. Test structures prepared by this
technique are listed in Tables 9A, 9B and 9C.
TABLE 9A
______________________________________
IAPVD Al.sub.2 O.sub.3 Wear layers on
Non-decorated Plastic Substrates
Sample
Wear Thickness LDP.sup.1
No. Layer (microns) Support
Substrate
(grams)
______________________________________
9-1 Al.sub.2 O.sub.3
1.5 PES.sup.2
2x tape/
15
glass
9-2 Al.sub.2 O.sub.3
4.9 None PSMC.sup.3
--
9-3 Al.sub.2 O.sub.3
6.0 None PSMC >35
9-4 Al.sub.2 O.sub.3
-- PVC.sup.4
WT.sup.5
--
9-5 Al.sub.2 O.sub.3
0.480 PVC WT 10
9-6 Al.sub.2 O.sub.3
0.528 PVC WT --
9-7 Al.sub.2 O.sub.3 /SiO.sub.x
0.432 PVC WT --
9-8 Al.sub.2 O.sub.3 /SiO.sub.x
0.336 PVC WT --
9-9 Al.sub.2 O.sub.3
4.03 None GFRP.sup.6
.about.35
9-10 Al.sub.2 O.sub.3
3.89 None FFP.sup.7
.about.30
9-11 Al.sub.2 O.sub.3
4.03 None PSMC >35,
<50
9-12 Al.sub.2 O.sub.3
1.78 None PSMC .about.40
9-13 Al.sub.2 O.sub.3
1.78 None PEEK.sup.8
30
9-14 Al.sub.2 O.sub.3
4.5 None Formica
23
9-15 Al.sub.2 O.sub.3
2.0 None Formica
--
9-16 Al.sub.2 O.sub.3
2.0 None Formica
--
______________________________________
.sup.1 Load to Substrate Penetration
.sup.2 Polyethersulfone
.sup.3 Polyester Sheet Molding Compound
.sup.4 Polyvinylchloride
.sup.5 Nonasbestos vinyl white tile base
.sup.6 Glass Fiber Reinforced Polyester
.sup.7 Fiber Filled Phenolic
.sup.8 Polyetheretherketone
TABLE 9B
______________________________________
IAPVD SiO.sub.x Wear Layers on
Nondecorated Plastic Substrates
Sample Thickness LSP.sup.1
No. (microns) Support Substrate
(grams)
______________________________________
9-17 2.3 Kapton.sup.2
2x tape/Glass
>15
9-18 1.2 None PMMA 15
9-19 2.3 None PMMA >15
9-20 1.1 None PMMA >15
9-21 1.8 None PMMA 10
9-22 1.2 Kapton 2x tape/Glass
25
9-23 1.2 PES.sup.4 2x tape/Glass
15
9-24 1.2 PEEK.sup.5
2x tape/Glass
15
9-25 1.2 Cronar.sup.6
2x tape/Glass
25
9-26 1.2 None Teflon7 <5
9-27 0.4 PVC.sup.8 WT.sup.9 5-10
9-28 1.4 PVC WT 10
9-29 2.3 PVC WT 15
9-30 3.8 PVC WT 15 g-18
9-31 3.7 PVC WT 15 g-18
9-32 2.8 PVC PSMC.sup.10
23
9-33 5.3 None PSMC .about.28
______________________________________
.sup.1 Load to Substrate Penetration
.sup.2 DuPont Polyimide
.sup.3 Polymethylmethacrylate
.sup.4 Polyethersulfone
.sup.5 Polyetheretherketone
.sup.6 DuPont Photographic Polyester
.sup.7 DuPont Polytetrafluroethylene
.sup.8 Polyvinylchloride
.sup.9 Nonasbestos Vinyl White Tile Base
.sup.10 Polyester Sheet Molding Compound
TABLE 9C
______________________________________
Miscellaneous IAPVD Coatings on Plastic Substrates
Sample Thickness
No. (microns) Structure
______________________________________
9-34 4.37 Al.sub.2 O.sub.3 /PVC/CWT
9-35 4.61 Al.sub.2 O.sub.3 /PVC/CWT
9-36 6.00 SiO.sub.x /PVC/CWT
9-37 <10 AlO.sub.x /PVC/CWT
9-38 .about.3 Al.sub.2 O.sub.3 /PVC/CWT
9-39 0.48 SiO.sub.x /Hologram
9-40 -- SnO.sub.x /Rigid PVC
9-41 -- SnO.sub.x /SiO.sub.x /PVC
______________________________________
For flooring structures with Al.sub.2 O.sub.3 or SiO.sub.x thin hard
coatings on selected plastic substrates: (1) an increase in wear layer
hardness resulted in an increase in gloss retention and overall appearance
retention; and (2) an increase in substrate hardness resulted in an
increase in gloss retention and overall appearance retention.
Gloss retention for flooring structures with thin hard wear layers occurs
because the hard coating resists penetration and subsequent removal. The
hard coating serves as a barrier that protects the less scratch resistant
plastic material. Therefore, the scratch test results reported here use an
alternative term, "Load to Substrate Penetration" (LSP) rather than "Load
to Incipient Damage" (LID). The LSP refers to the weight loading at which
the diamond stylus penetrates the hard protective layer and enters the
substrate below. For example, irreversible damage is caused by a stylus
load of 15 grams for a Al.sub.2 O.sub.3 coating on PSMC, and this low LID
implies that poor gloss retention will be observed. However, the opposite
is true. Gloss retention by thin, hard coatings depends upon both coating
and substrate properties, and the LSP reflects that synergistic
relationship better than does the LID.
Tables 9A, 9B and 9C contain the LSPs for most of the coatings that have
been prepared.
Results from the scratch tests are clearly in agreement with the Walkers
Test data regarding the superiority of Al.sub.2 O.sub.3 as a wear layer.
The LSP for Al.sub.2 O.sub.3 on PSMC is higher than that of SiO.sub.x.
The results for SiO.sub.x on both PSMC and PVC/CWT show that scratch
resistance improves with the thickness of the hardcoat. This is consistent
with the observation of improved gloss and appearance retention for thick
vs thin coatings on soft plastic supports.
The high LSPs for both SiO.sub.x and Al.sub.2 O.sub.3 on PSMC predict, in
agreement with Walkers Test data, that the PSMC should be the best
support.
EXAMPLES 10-1 TO 10-4
This Walkers Test demonstrated that good gloss retention is obtained from a
flooring structure consisting of a Al.sub.2 O.sub.3 wear layer supported
by a rigid plastic, like polyester sheet molding compound (PSMC). The
performance rating of the Al.sub.2 O.sub.3 coated metal substrates was
complicated by the fact that water vapor contamination was present during
some of the runs. The TiN.sub.x, blue-black in color, had gloss
performance similar to Al.sub.2 O.sub.3.
A structure consisting of 4-microns of Al.sub.2 O.sub.3 on a thick plate of
polyester sheet molding compound (PSMC) remained essentially free of small
scratches, showing no hazing and retaining 86% of its measured gloss after
1200 walker cycles. It had, however, a number of individually visible
scratches.
Al.sub.2 O.sub.3 wear layers on (a) fabric filled phenolic (FFP), (b) black
PSMC, and (c) glass fiber-reinforced polyester retained a lesser but still
substantial portion of their original gloss. The uncoated controls, in
contrast, were completely deglossed and covered with fine scratches that
resulted in a final hazy appearance.
The samples were tested in the Walkers Test. Gloss measurements were
obtained for the samples and listed in Table 10.
TABLE 10
______________________________________
Gloss values for 4 micron thick Al.sub.2 O.sub.3 coated and
uncoated rigid polymer substrates before and after
Walkers Test trafficking
Sample
No. Description Initial Final
Change % Loss
______________________________________
10-1 Al.sub.2 O.sub.3 /White PSMC.sup.1
46.5 39.7 -6.8 -14.6
C10-1 White PSMC 57.5 2.5 -55.0 -95.7
10-2 Al.sub.2 O.sub.3 /Black PSMC
46.8 37.9 -8.6 -18.4
C10-2 Black PSMC 64.2 2.6 -61.6 -96.0
10-3 Al.sub.2 O.sub.3 /GFP.sup.2
25.1 16.7 -8.4 -33.5
C10-3 GFP 20.2 11.6 -8.6 -42.6
10-4 Al.sub.2 O.sub.3 /FFP.sup.3
69.1 45.6 -23.5 -34.0
C10-4 FFP 52.1 9.7 -42.4 -81.4
______________________________________
.sup.1 1/4" Thick Polyester Sheet Molding Compound
.sup.2 1/4" Thick Glass Filled Polyester
.sup.3 1/4" Thick Fabric Filled Phenolic
EXAMPLE 11
Al.sub.2 O.sub.3 and SiO.sub.x wear layers on PSMC showed no significant
gloss reduction after 1200 walker cycles, however there were some visible
scratches. Test flooring structures using commercial wear layer materials
all were completely deglossed and visibly scratched to a matte finish
after the same test period. Also between those extremes was a second new
flooring structure with a 5-8.mu. wear layer of SiO.sub.x on a relatively
non-rigid substrate (non-decorated rigid PVC film laminated to
non-asbestos vinyl white tile base). Al.sub.2 O.sub.3 clearly
out-performed SiO.sub.x for structures having a common substrate, and
comparable wear layer thickness. The observations from this and other
Walkers Tests clearly demonstrate that important aspects in the
performance of hard inorganic wear layers on plastic substrates include
wear layer thickness, wear layer hardness, and support rigidity.
Superior gloss retention and scratch resistance have been observed with new
structures consisting of a reinforced plastic support and an inorganic
wear layer. The support material was polyester sheet molding compound, and
the wear layer consisted of a five to eight micron "thick" film of either
Al.sub.2 O.sub.3 or SiO.sub.x, prepared by IAPVD.
The SiO.sub.x and Al.sub.2 O.sub.3 coatings on PSMC were above the critical
thickness required for wear resistance applications. Above that thickness
limit, further increases in coating thickness have no apparent effect on
either gloss retention or scratch resistance. Scratch tests suggest that
the crossover point is in the one to three micron range.
Hardness of the coating material is a factor in determining gloss retention
and scratch resistance. For example, despite being 2 microns thinner than
its SiO.sub.x coated analog, the 5-6 micron "thick" Al.sub.2 O.sub.3
coated PSMC samples started and finished the Walkers Test at higher gloss,
and with fewer visible scratches. This is consistent with the previous
observation that IAPVD Al.sub.2 O.sub.3 is a harder material than IAPVD
SiO.sub.x.
Samples approximately six inches square were tested in the Walkers Test
using the serpentine sample arrangement. Tables 11A and 11B list average
gloss readings from the Walkers Test.
PSMC was obtained as 12".times.12".times.0.125" panels of L15402
Premi-Glass 1100-05, Cameo Colored, from Premix, Incorporated.
Al.sub.2 O.sub.3 and SiO.sub.x wear layers were evaporated from the e-beam
gun without the use of crucible liners, and the chamber was cleaned and
refoiled immediately prior to each deposition to avoid water vapor
contamination.
TABLE 11A
______________________________________
Gloss Values for Polyester Sheet Molding Compound
(PSMC) and Ceramic Wear Layers on PSMC after
Walkers Test Trafficking
8 micron Thick
5-6 micron Thick
Control PSMC SiO.sub.x on PSMC
Al.sub.2 O.sub.3 on PSMC
Passes
Initial Final Initial
Final Initial
Final
______________________________________
0 60.7 -- 47.9 -- 54.1 --
24 62.0 51.0 46.6 47.9 53.3 53.7
48 61.5 34.1 48.0 49.1 60.3 60.8
102 66.3 15.7 38.5 42.2 46.6 46.9
204 58.7 7.8 48.6 50.8 55.4 55.9
402 50.5 3.1 53.2 52.6 61.0 61.7
804 65.9 3.1 55.2 50.8 43.2 44.8
1200 60.0 2.8 53.1 49.0 58.7 59.4
______________________________________
TABLE 11B
______________________________________
Gloss values for SiO.sub.x on PVC, and Polyethersulfone
after Walkers Test Trafficking
4-6 micron Thick 3 mil Thick PES on
SiO.sub.x on PVC Citation Tile Base
Passes Initial Final Initial
Final
______________________________________
0 52.3 -- 98.7 --
24 52.5 52.8 98.8 22.9
48 59.4 60.3 102.0 20.5
102 56.8 42.2 100.1 05.6
204 56.8 42.2 109.0 04.5
402 53.5 34.9 91.2 01.4
804 48.1 21.9 95.5 00.3
1200 46.1 13.2 94.6 00.4
______________________________________
EXAMPLES 12-1 TO 12-28
Samples approximately six inches square were tested in the Walkers Test.
Initial and final gloss readings were made using a Mallinckrodt 60.degree.
C. Pocket Gloss Meter and B. A. Newman's template. Table 12A lists average
gloss readings for the samples. Descriptions of the samples are given in
Table 12B.
Alumina wear layers were deposited onto the samples by evaporating Al.sub.2
O.sub.3 from the E-beam gun without the use of crucible liners. The
procedure included a bakeout at 250.degree. C. for 1 hour prior to each
deposition to minimize water vapor contamination. For most runs, the
substrate temperature was allowed to "float" starting at
30.degree.-40.degree. C. during the deposition runs. For depositions done
without the ion gun, an O.sub.2 atmosphere of .sup.-2.3.times.10.sup.-4
Torr was maintained. Plasma cleaning, when employed, was for five minutes
at a pressure of about 3 -6.times.10.sup.-4 Torr.
The substrates consisted of about 30 mils of Heraeus H34000 series White
Overglaze Frits on a 7 mil stainless steel base. Ink fusion was done using
either ovens or moving belt furnace.
Thickness measurements were done using the
Amray Scanning Electron Microscope (SEM) or the Nikon Polarized Light
Microscope (PLM).
TABLE 12A
______________________________________
60.degree. Gloss at Walker Count
Example No. 0 200 800 1200
______________________________________
12-1 91.4 -- -- 84.5
12-2 93.2 -- -- 91.3
12-3 98.0 -- -- 95.6
12-4 98.7 -- -- 94.1
12-5 to -7 108.2.sup.a
106.3 89.3 105.3
12-8 to -10
103.6.sup.a
100.8 99.9 107.8
12-11 to -13
99.9.sup.a
105.7 98.3 105.1
12-14 to -16
101.6.sup.a
70.7 102.6 107.8
12-17 to -19
95.2.sup.a
100.5 97.0 103.4
12-20 to -22
86.5.sup.a
94.9 84.1 94.3
12-23 to -25
88.7.sup.a
100.2 88.6 86.0
12-26 to -28
90.1.sup.a
81.5 99.5 90.6
______________________________________
.sup.a average of three samples
TABLE 12B
__________________________________________________________________________
Wear Layer
Deposition
Deposition
Ion O.sub.2 +
Example
Thickness
Rate Temperature
Cleaning
Ion Al.sub.2 O.sub.3
No. (microns)
(A/S).sup.c
(.degree.C.)
Gas Assist
Purity
__________________________________________________________________________
12-1 2.2 7.2 59-196
Ar Yes 99.99%
12-2 4.9 31 90-123
Ar Yes 99.99%
12-3 3.6 12 113-129
Ar Yes 99.99%
12-4 5.3 33 114-134
Ar Yes 99.99%
12-5 3.4 15 70-129
Ar Yes 99.8%
12-6 3.4 15 70-129
Ar Yes 99.8%
12-7 3.4 15 70-129
Ar Yes 99.8%
12-8 3.4 15 61-134
Ar Yes 99.5%
12-9 3.4 15 61-134
Ar Yes 99.5%
12-10
3.4 15 61-134
Ar Yes 99.5%
12-11
3.4 15 138-170
Ar Yes 99.99%
12-12
3.4 15 138-170
Ar Yes 99.99%
12-13
3.4 15 138-170
Ar Yes 99.99%
12-14
7.7 17 71-170
Ar Yes 99.99%
12-15
7.7 17 71-170
Ar Yes 99.99%
12-16
7.7 17 71-170
Ar Yes 99.99%
12-17
2.9 40 130-170
Ar Yes 99.5%
12-18
2.9 40 130-170
Ar Yes 99.5%
12-19
2.9 40 130-170
Ar Yes 99.5%
12-20
11.6 40 100-206
Ar Yes 99.5%
12-21
11.6 40 100-206
Ar Yes 99.5%
12-22
11.6 40 100-206
Ar Yes 99.5%
12-23
3.3 30 95-160
Ar No 99.5%
12-24
3.3 30 95-160
Ar No 99.5%
12-25
3.3 30 95-160
Ar No 99.5%
12-26
8.6 60 250 Ar Yes 99.5%
12-27
8.6 60 250 Ar Yes 99.5%
12-28
8.6 60 250 Ar Yes 99.5%
__________________________________________________________________________
The results showed that gloss retention performance is relatively
insensitive to Al.sub.2 O.sub.3 deposition parameters. Thickness between 3
.mu. and 12 .mu.; deposition rates between 7.ANG./S and 60.ANG./S; and
Al.sub.2 O.sub.3 purity between 99.5 and 99.99% (for isostatically pressed
powders or crystals) did not effect Walkers Test performance.
EXAMPLES 13-1 AND 13-2
Samples were tested in the Walkers Test. One sample each was pulled at 200
and 800 counts while two samples were trafficked to 1200 counts.
PBMC was decorated by sublimation imprinting. Al.sub.2 O.sub.3 wear layers
were evaporated by electron beam. No bake-out was used prior to
evaporation.
Table 13A lists the data and gloss values for the samples tested. Stain
resistance tests were done by applying each reagent for a period of four
hours. The samples were cleaned with Micro and water followed by acetone.
Delta E values were calculated from L, a, b readings on a Hunter
Laboratory, Model D25 optical sensor. Table 13B lists the samples tested
for stain resistance and their Delta E values.
TABLE 13A
______________________________________
Wear Layer
Example Thickness 60.degree. Gloss at Walker Count
No. Description
(microns) 0 200 800 1200
______________________________________
13-1 Al.sub.2 O.sub.3 /Sub.
4.7 .+-. 0.3
54.6 45.9 48.8 49.5
Imprint/
PBMC
13-2 Al.sub.2 O.sub.3 /
4.0 .+-. 0.3
61.1 56.7 56.5 51.7
Marble
PBMC
______________________________________
TABLE 13B
__________________________________________________________________________
Sanford Shoe Hair Ball
Example
Ink Iodine
Polish
Dye Point Ink
Asphalt
Total
No. Delta E
Delta E
Delta E
Delta E
Delta E
Delta E
Delta E
__________________________________________________________________________
13-1 9.34 2.17 3.91 2.39 8.77 1.87 28.53
13-2 6.75 1.35 2.94 1.30 17.39
2.64 32.37
__________________________________________________________________________
No difference was observed in wear performance or adhesion of Al.sub.2
O.sub.3 applied over decorated (sublimation imprint) and non-decorated
PBMC. Overall wear performance was good. Wear performance of marbled PBMC
with Al.sub.2 O.sub.3 was similar to that of sublimation imprinted PBMC
with Al.sub.2 O.sub.3.
The samples maintained a fairly level gloss curve. The samples had very few
fine scratches. The large scratches were not numerous. The scratches
become readily visible when they penetrated the Al.sub.2 O.sub.3 and
destroyed the print. The white color of the scratches was apparently
caused by stress whitening of the PBMC.
EXAMPLES 14-1 TO 14-14
Examples 14-1 to 14-7 were formed by depositing two to three microns of
SiOx by E-beam evaporation using a Web coater onto the 24-inch wide, 7-mil
filled mylar sheets. Coating speed was about 30 ft/min.
Examples 14-8 to 14-14 were formed by depositing 3 microns of SiOx by
E-beam evaporation onto back side of samples formed by the procedure of
Examples 14-1 to 14-7. The procedure utilized a freshly cleaned and
refoiled deposition chamber, an O.sub.2 ion assist, but not a bakeout. The
samples were not precleaned prior to loading into the deposition chamber,
and were not subjected to a plasma cleaning step after loading.
The SiOx on mylar was adhered to a bulk molding compound using adhesive
release tape. Table 14 gives average gloss values at each traffic
interval.
TABLE 14
______________________________________
60.degree. Gloss at Walker Count
Example No.
0 200 400 800 1200
______________________________________
14-1 to 14-3
19.1 31.3 -- 17.2 10.3
14-4 to 14-7
23.7 16.7 14.9 9.9 4.7
14-8 to 14-10
35.4 40.9 -- 27.0 29.5
14-11 to 14-14
29.2 33.7 26.3 21.2 9.5
______________________________________
EXAMPLES 15-1 TO 15-15
Six-inch square samples were tested in the Walkers Test. Table 15 lists the
sample descriptions and the respective gloss values.
Examples 15-1 to 15-12 were prepared with 7-mil, 302 stainless steel
substrates. Examples 15-13 to 15-15 were prepared with 14-mil cold rolled
steel supplied by Chicago Vitreous with their ceramic ground coat. The
substrates were coated as follows:
Examples 15-1 to 15-4: 30 micron-H34002 primer and 10 micron-H34002
textured pattern with 20% matting agent H7003.
Examples 15-5 to 15-8: 30 micron-H34002 primer and 10 micron-H34002
textured pattern with 20% matting agent H7003 and a 5.95 micron thick
clear, Heraeus H30011, protective ceramic glaze.
Examples 15-9 to 15-12: 30 micron-H34002 primer and 10 micron-H34002
textured pattern with 20% matting agent H7003 and a 2.40 micron thick
aluminum oxide layer.
Examples 15-13 to 15-15: 56.6 micron of ground coat, 29.1 micron-H34002
primer as the wear layer.
The primer and matting agent were manufactured by Heraeus.
TABLE 15
______________________________________
Total Nominal Al.sub.2 O.sub.3
Enamel Wear Layer
Example
Thickness Walker 60.degree. Gloss
Thickness
No. (Micron) Cycles Initial
Final
(Micron)
______________________________________
15-1 40 200 52.8 67.5
15-2 40 800 66.5 64.4
15-3 40 1200 64.8 67.7
15-4 40 1200 61.0 59.7
15-5 40 200 57.4 65.6 5.95
15-6 40 800 55.2 53.3 5.95
15-7 40 1200 65.3 63.5 5.95
15-8 40 1200 61.7 64.6 5.95
15-9 40 200 71.9 75.1 2.40
15-10 40 800 72.5 71.0 2.40
15-11 40 1200 67.8 73.0 2.40
15-12 40 1200 66.3 66.6 2.40
15-13 86 200 89.8 95.5
15-14 800 90.6 96.0
15-15 1200 88.6 87.1
______________________________________
As shown in Table 15, the gloss values of the three
stainless-steel-substrate categories are essentially unchanged after a
total traffic count of 1200. Appearance retention differences between the
categories were noted however. The stainless-steel structure without a
wear layer, exhibited more visually objectionable scratches than the
glaze-coated and aluminum oxide-coated structures. These later two
categories had hard protective wear layers which appear to afford
increased scratch resistance.
Although the low-carbon-steel structure exhibited excellent gloss
retention, scratch resistance was poor compared to the other structures.
Most of the scratch damage was limited to the upper-most ceramic layer
which was the Heraeus H34002 system. The type of damage present indicated
a poor level of adhesion between the ground coat and the Heraeus ceramic.
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